


just sans

by legendary_artifact (cynicwithasecret)



Category: Undertale (Video Game)
Genre: Bad Jokes, Childhood Trauma, DESCRIPTIVE AF, Daddy Issues, F/M, Gen, Substance Abuse, i wrote this in comic sans y'all send help pls, rating and tags will change
Language: English
Status: In-Progress
Published: 2020-11-08
Updated: 2020-11-08
Packaged: 2021-03-08 22:06:27
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,487
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27460168
Author URL: https://archiveofourown.org/users/cynicwithasecret/pseuds/legendary_artifact
Summary: It's the backstory that no-one needs but maybe someone wants!Daddy issues, junk food, substance abuse, a failed relationship and several battles with depression, all sprinkled with sciencey fun and a heaping of monster culture. Strap in folks, this is going to get intense. And spooky. Maybe. We'll see.
Relationships: Papyrus & Sans (Undertale), Sans & Original Undertale Character(s), Sans (Undertale)/Original Character(s), W. D. Gaster & Papyrus & Sans, W. D. Gaster & Sans
Comments: 2
Kudos: 10





	just sans

**Author's Note:**

> this fandom is alive and well and totally not toxic at all so don't let me tell you otherwise

Workers in the CORE were accustomed to the blackouts.

They happened irregularly, once every few weeks, and after decades of random plunges into darkness, they never surprised the puzzle-placers, engineers and janitors of Hotland. A sputter of magical electricity followed a thunderous metallic groan, and the hulking metal behemoth powering the whole Underground would go dark. Glowing crystal lamps lit up in the hands of the monsters roaming the CORE, and workers waited near the warmth of open lava in a patient silence broken only by rushing steam and the popping of molten bubbles. There was no cause for panic. Without fail, everything would miraculously power up again after a few minutes, and life continued as normal. 

What caused the blackouts? There were plenty of theories, possibilities and suppositions to go around, and there still are. There is nothing the old monsters of the Underground relish more than gossip. Horror stories come a close second, and there were plenty of those as well. Workers whispered that there was a feral ghost messing with wires, while others claimed there was some terrible beast swimming in the magma itself, chewing on cables. Some said that Doctor W. D. Gaster, the famed creator of the CORE himself, was siphoning off the CORE’s power for a secret project of his own involving [ ~~ **ERROR**~~ ]. Those guesses were probably closer to the truth than most. 

Coincidence or not, it was during one of those dark shuddering moments, when all the lights flickered off and the whole CORE groaned in exhaustion from an unknown labour, that Sans the skeleton was born. 

The CORE itself had birthed the little menace, some workers joked. 

There was no other obvious candidate as a mother. Since the war had wiped out the rest of the skeleton clan, Doctor Gaster had been the last of his kind, and more importantly, everyone knew the old genius liked his solitude. In over one hundred and fifty years, he had never apparently taken a lover, or expressed any desire for fatherhood. And yet one day there he was, walking through the palace for his usual weekly meeting with King Asgore, holding a smiling skeleton baby in his arms. It should have been impossible. But if anyone could have figured out a way to continue their own clan, it _would_ be the Doctor. 

The child was special, people said. The child was important. 

Heh. 

Well. It doesn’t matter much now. 

~#~

_Loading narrator…_

_Compiling backstory…_

_Process complete._

Life actually began for Sans on a schoolday when he was twelve. 

That was not strictly true, because he was definitely alive before that day, but the interesting stuff only really began afterwards. Everything which came before - childhood traumas and discoveries, conflicts and good times with his father, first steps and first mistakes - it was nothing to write home about. There was nothing unique about any of it, in his own opinion. Sure, he might have had a fairly unconventional upbringing, but what kid in the world could say they had a perfectly happy, textbook childhood? What kid did not have traumatic memories to haunt their nightmares and wake them in the night with shivering and cold sweats? 

Yeah. Totally normal. 

And anyway, he had turned out alright, as far as Sans could tell. 

On the brink of his teenage years, somehow straddling the roles of class clown and star pupil, Sans was extremely popular at school. Everyone knew him. Everyone liked him. There was nothing intimidating about the short skeleton boy with the baggy hoodie, so the shy kids were never afraid to approach him for a corny joke or some help with their homework. Meanwhile, he was confident and funny enough that the cool kids still thought he was worth knowing, and because he acted so unimpressed by them, they became convinced he was way cooler than they were. More or less living full-time in a restricted lab was kind of neat as well - most of the kids at school were in awe of that. And the real killer? Rumour had it that he already smoked. At _twelve_. In the eyes of a bunch of bored pre-teens, that basically made him a god. 

So naturally, Sans had friends, although perhaps it was weird that most of his friends were grown-ups. Despite his schoolyard popularity, he found it difficult to relate to children his age, or children period. His best friends were the grown-up ones, the CORE workers, his “other parents” as he liked to call them. 

The first one to take him under her wing, pun intended, was a little bat-monster called Ferris, the puzzle master of the CORE. He had only been a toddler when she first took his tiny hand and led him to the puzzle store, where she introduced him to the generations-old Underground tradition of puzzle exchange. Ferris was a mother already to ten babies, so one more was no challenge. She made sure he was safe wandering in the shifting metal corridors and exchanged crosswords with him in the storeroom when he felt like hiding from everyone else.

A mechanic with an attitude, Mavra had been a tougher challenge to befriend. A tall bear monster, young and abrasive, quick to take offence but quicker to accept a hot beverage, she had initially done nothing but growl at the little skeleton child who had a bad habit of appearing without warning from the shadows. But even she had eventually succumbed to Sans’ baby charm when the bony shrimp of a monster looked up at her with a missing front tooth, offering a steaming cup of cocoa. Since then, Mavra’s growling had come from a place of fondness rather than irritation.

Then there was Ol’ Stan the janitor, whose big scaly belly had always been a great napping stop during weekend lunch breaks, and whose crazy stories and booming laughter had left Sans senseless with giggles. The skeleton boy had tried his first sip of beer under Ol’ Stan’s watchful guard, both of them keeping a lookout for more responsible adults who might have put a stop to their antics. On his twelfth birthday, the old reptile made him the greatest gift he had ever received. It was a joke book, entirely written from scratch and bound at the spine with fuzzy green pipe-cleaners. Every page was illustrated by hand and coloured with crayon, every joke set out in laborious, blocky handwriting, complete with the occasional soot stain from Ol’ Stan’s overworked claws. 

Knowing how much effort had gone into it, how much love had motivated the poor old janitor to sacrifice his lunch and coffee breaks to finish it on time, Sans intended to keep it in his jacket for all eternity. It had its own big custom-stitched pocket, and rested over his ribcage, ready to produce when comedic timing demanded a tried-and-tested gag. 

On the afternoon when his life began, Sans had taken out the joke book for a while. The New Home School for Young Monsters had closed for the day. It was home time, and like always, the Hotland kids were walking together in a group towards the elevator network, supervised at a distance by a burly but quiet bird-type member of the Royal Guard. Although Dorotka had been assigned to direct the children away from dangerous parts of the caves while they walked home, the kids tolerated her because she had been known to offer them sweets, and rarely spoke, which was even better, because then they could pretend there were no adults around to stifle their fun.

During the stroll to the elevator hub, Sans was dropping jokes like there was no tomorrow, making the most of the free time away from the lab. He could have just hidden from the other children and teleported straight home, but where was the fun of that? During the walk, he could pretend for a short time that he felt like a child. At the very least, he could make a few friends laugh and get bits of sticky candy between his teeth (arguably a worse problem for skeletons than it was for monsters with lips). Even if there was nothing very exciting about the elevator journey to Hotland, there was no reason to rush back to his father. Besides, it was the principle of the thing - he was a rebellious brat, and rebellious brats came home late. 

So, the jokes: 

“five out of four people admit they’re bad with fractions.” 

“what do you call a dog magician? a Labracadabrador.” 

He was on a roll, the Hotland kids either groaning from the cringe or clutching their sides in hysterics. Sans, meanwhile, just grinned his usual quiet grin. The children thought he was too cool and mature for laughing out loud. It had been a while since he had felt the urge. 

“I had to quit my job at the helium farm,” he continued. “I refuse to be spoken to in that tone.” 

Some of them got that one, but one little earth elemental kid turned greenish in confusion. “Huh? I don’t get it,” the boy mumbled. 

“Dude,” said a furry monster two years older than Sans, “helium makes your voice _really squeeeeaky_.” 

“Oh!” the little kid laughed self-consciously. “Haha! Good one.” 

As the elevator doors whooshed open, someone handed Sans another stick of chewy taffy, which he struggled with for a few minutes. The others chattered on about a school trip to Waterfall which was in the works, one which Sans knew he would not be going on. It did not matter to him. School trips were lame anyway and spending more time studying with his father was fine. Just fine. 

Someone tried to ask him about his evening plans, so of course rather than answering he just reverted to the jokes. 

“did I tell you about the velcro I bought last week? it was a total ripoff.” More groans than laughs for that one. Bad crowd.

“why do crabs never share?” 

“Because they’re _shellfish_ ,” blurted out Effie, a cute cat girl with a blue ribbon clipped to one ear. 

“nice,” he said. Sans winked at her, but only because he winked at everyone. And the smile was a permanent thing on his face. Nothing he could do about that. If she got flustered and giggled, it was _not_ because he was flirting, even if the other kids started mouthing off and teasing them about it. 

Thankfully, they lost interest after a short while, and started talking about the latest radio show they were obsessed with. And hey, they were not spoiled for choice. Monster media at the time was limited to a single cheesy TV broadcast of dry news and reruns of King Asgore’s speeches, and three warring radio stations. There were only a few shows that appealed to young people, and monster music - well, it sucked, to put it mildly. Boredom was a real problem for the Underground children. They lived in a small, unchanging world, born to bored parents and boring destinies. Hope, their teachers said, was the antidote to their misery. One day, the barrier would fall, and monsters would take the surface world back from humanity.

They might as well have been talking about moving to the stars.

The New Home School was a site of blatant indoctrination, Dr Gaster insisted. It was one topic he hotly debated with the King, when they had their weekly meetings, but nothing had ever come of their disagreement. Sans knew that his father could not wait until he left school to help him out in the lab. Fifteen was the normal age for that to happen, when teen monsters gained apprenticeships or other work, or just continued to exist without function. Paying jobs were scarce in the overcrowded Underground capital. Luckily (or unluckily) for him, Sans already had his apprenticeship and future neatly lined up for him. 

Whatever. He was unsure if he agreed with his father’s assessment of the education system, but would admit that he had learned far more about combating cave damp and being a responsible citizen from school than he had about mathematics or science. His father had supplemented those aspects of his education. Gaster had tried to teach him lots of other useful, practical things, such as the fact that most other monsters were unintelligent sheep who could not be trusted with their own lives. That was a hard lesson to unlearn. So were many others. 

Fortunately, Sans had learned very different things from his other parents, and he liked to think it had balanced him out a bit, given him some objectivity. 

“Yer way too mature for yer own age, kid,” said Ferris when he told her about that kind of stuff. “Don’t go growin' up so fast.”

Sans was pretty sure it had never been a choice.

~#~

Effie touched his arm when she said goodbye, and Sans did his best to play it cool while the others laughed and made exaggerated kissing noises. 

“See you tomorrow, dude!” 

“Bye Sansy!” 

“bye guys,” he called after them, and turned to the CORE. 

There it was, built into the cave wall, the enormous crowning achievement of his father’s life, huge and grey and blinking with lights. A canyon of lava and stinking sulfurous gases seethed below. It was probably a good thing that he lacked corporeal lungs, otherwise the fumes would have given him some kind of breathing disorder by now. A few of the older workers had issues like that, particularly those who worked outside near the bottom of the structure. There was artificial ventilation within the enclosed metal maze, but it was difficult to purify air in a lava-filled cave constantly spewing up noxious gas. 

Mind you, some of his “other parents” were clearly unbothered enough by the respiratory risk to loiter outside, chain smoking on their breaks. His father likely disapproved, but the Royal Scientist had never embraced a managerial role with any enthusiasm. What the CORE team did, as long as he never saw it, as long as it did not interfere with his work, was none of his concern. One of his quirks. 

And yeah, it was kinda boring to think about a few stinky gases, but Sans, despite his school reputation, was a huge nerd. The boredom, as already established, was a constant struggle for the Underground children. It had gone so far sometimes that he had resorted to reading some of his father’s old notes. _The composition of lava is dominated by silicate minerals: mostly feldspars, olivine, pyroxenes, amphiboles, micas and quartz. High viscosity lava tends to flow slowly, clog, and form semi-solid blocks which resist flow. However, a degassed viscous lava or one which erupts somewhat hotter than usual may form a lava flow. That appears to be the case here._

Thrilling stuff, huh? I bet you skipped it.

Even ignoring the air quality, the CORE was an unsafe place to raise a child. Puzzles, lasers and traps filled the interchangeable rooms, often chaotically arranged. Which meant, of course, that it was an extremely fun place to live. Ever since Ferris taught him to create puzzles and alter the room-change levers, Sans had pranked the unsuspecting staff with shifting puzzles so many times they had given up trying to stop him. Little menace, they called him. 

“ _Psotnik_ ”, Mavra growled as he walked past. She was sweet like that. 

Sans made his way through the CORE, schoolbag on his back. The puzzles were deactivated on weekday afternoons, so there was nothing to worry about there. He descended a ladder and reached the entrance to his father’s office. It was a thick, locked, armoured door with a code lock, of the kind which took many years to forge. It was the type of door which screamed that there were secrets behind it - which was true. That it existed at all was a big deal. Any kind of construction took a long time in the Underground due to a lack of resources and motivation. But despite the setbacks, Doctor Gaster had a way of persevering at construction, at creation. Hence the CORE. Hence the lab underneath it. Hence Sans. 

His father owned of a place of residence other than the lab, a neglected house in New Home. Long before the birth of his son, the Royal Scientist had used it primarily as a glorified storeroom, and never locked the doors, so the workers from the CORE made use of it as a clubhouse, leaving unfinished card games in the hallway, dumping belongings haphazardly on the furniture and storing food in the cupboards. The house had never felt like a living space to Sans. The kitchen stove was dusty. The fireplace was full of equipment. Meanwhile, all of Sans’ toys, books and hobbies were here at the lab, and his father was here too. 

That was the thing. Sans truly loved his dad. 

Don’t get it sideways. Controlling, obsessive, insensitive, cold - all of these adjectives were true. Also true were words like brilliant, genius, eccentric. Yes, there was resentment between them, but didn’t every son resent his father to some extent? The word _abusive_ had never been in the young skeleton’s vocabulary. Some things in the past were hard to forgive or understand, and Gaster may have been the most difficult, grating person in the whole Underground, but the maniac was _his dad_ , goofy and predictable and forever pursuing one of his unreachable goals. 

And everything he had done was for a good reason. Right? 

Yeah. 

Anyway, there was a page on a workbench scrawled in his father’s cipher. 

_Surprise downstairs - G._

Sans decided to act as if he had not seen the note. Very few of his father’s “surprises” had ever been enjoyable ones. He dumped off his school things and put on a big show of shutting the fridge door hard, making sure his father could hear that he was home. He put his feet up on a desk, displacing pens and blueprints, and began demolishing some stale cookies. 

Within a few minutes, Dr Gaster appeared in a doorway. While the Royal Scientist was not a tall or intimidating person by monster standards, he was very good at establishing his presence in a room without saying a single word. 

Sans and his father looked at each other for a while in silence. Or in something close to silence. It was never entirely quiet in the lab, with the constant hum of the CORE in the background and all the whirs, crackles, bubbles and pops of machinery and experiments lying around. 

_Did you see my note?_ Gaster signed using his floating, spectral hands, rather than speaking out loud. 

“nope,” Sans shrugged, messily crunching a cookie, crumbs spilling from his teeth onto his clothes. 

The look of utter disappointment levelled at him could have crushed reinforced steel. Gaster’s eye lights darkened briefly. 

_You know the rules, Sans. Signs when it’s just the two of us._

Sans sighed and summoned his own spectral hands. It was easier to keep eating that way. _fine_ , he gestured. _what’s the surprise?_

Gaster gestured with his head and turned back towards the stairs, walking away without waiting for a reply. Apparently Sans would have to follow if he wanted to get an answer. Typical. Sighing, he set aside the cookies and resigned himself to whatever wonderful plans his father had cooked up for the evening. If he was lucky, whatever it was wouldn’t be too exhausting, and he could sneak off early to take a nap somewhere. 

Nothing could have prepared him for what was waiting downstairs. 

In a little cot, wriggling excitedly, was a newborn skeleton baby.

Sans was speechless, completely speechless. There had been no warning at all, no sign from his father that he was planning to have another child. But that was always the way, wasn’t it? Gaster never told him anything, he just acted, and forced his son to witness the consequences.

The Doctor lifted the baby and signed for Sans to come closer. _Come meet your brother._

And then, before he had processed what was happening, the baby - his brother - was in his arms, squirming and alive. Sans could not stop staring at his tiny skull or his miniature grasping fingers with their pointy tips. A brother. He had a little brother. 

“What’s his -” 

_Signs, Sans._

_What’s his name?_ Sans asked. 

“ _Papyrus_.” Gaster both signed and spoke the name, his usual dry tone tinged with pride. 

The baby reached up and touched Sans’ face, mirroring his permanent grin by clacking his teeth together and making happy gurgling noises. 

“hey there,” Sans mumbled, unable to articulate his emotions.

But all at once, he was overcome with a great certainty. From that very first moment, he was sure that he would willingly die for this child, for his little brother. For Papyrus. 

When it came down to it, turned out he was wrong. He would willingly _live_ for Papyrus instead.

**Author's Note:**

> be a dear and leave kudos (or a comment) <3


End file.
